Method and apparatus to reduce or eliminate stiction and image retention in interferometric modulator devices

• US 7,855,826 B2
• Filed: 08/12/2008
• Issued: 12/21/2010
• Est. Priority Date: 08/12/2008
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Gudlavaleti, Sauri, de Groot, Wilhelmus A., Tung, Yeh-Jiun
• Primary Examiner(s): Ben; Loha
• Application Number:
  US12/190,407
• Publication Number:
  US 20100039696A1
• Time in Patent Office: 861 Days
• Field of Search: 359290-295, 359/298, 359/224.1, 345/55, 345/173, 427/162
• US Class Current: 359/291
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 3/0008 Structures for avoiding electrostatic attraction, e.g. avoiding charge accumulation
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26

Abstract

Method and apparatus to reduce or eliminate stiction and image retention in interferometric display devices are disclosed. In some embodiments, a display element comprises a plurality of interferometric modulator devices configured in a matrix, each interferometric modulator device having a movable reflective layer and a plurality of supporting posts, the plurality of posts defining a post spacing distance in at least one direction that is greater for one or more interferometric modulator devices disposed adjacent to an edge of the display element than one or more interferometric modulator devices disposed nonadjacent to an edge of the display element.

Claims

1. A display element comprising:

a plurality of interferometric modulator devices configured in a matrix forming a plurality of rows and columns, each interferometric modulator device comprising

a movable reflective layer comprising two opposite edges that are each supported by a rail and two opposing free edges; and

a plurality of posts configured to support the movable reflective layer, the plurality of posts being spaced apart to define post spacing distances between adjacent posts positioned along an axis parallel to one of the rails, wherein the post spacing distance between adjacent posts along the axis and closest to each free edge is smaller than the post spacing distance between a plurality of other adjacent posts along the axis.

2. The display element of claim 1, wherein the post spacing distances between said plurality of other adjacent posts along the axis are substantially the same.

3. The display element of claim 1, wherein the post spacing distances between the adjacent posts along the axis and closest to the respective free edges are substantially the same.

4. The display element of claim 1, wherein the post spacing distances between adjacent posts along the axis increase as the distance from one of the free edges increases.

5. The display element of claim 4, wherein the post spacing distance between said plurality of other adjacent posts along the axis is approximately 38 μ

m.

6. The display element of claim 1, wherein the post spacing distance between the adjacent posts along the axis and closest to each free edge is approximately 32 μ

m.

7. The display element of claim 1, wherein the post spacing distance between the adjacent posts along the axis and closest to each free edge is approximately 2-10 μ

m smaller than the post spacing distance between said plurality of other adjacent posts along the axis.

8. The display element of claim 1, wherein the defined post spacing distances minimize a voltage required to release the interferometric modulator device.

9. The display element of claim 1, wherein the post spacing distances are defined such that at least one free edge of the movable reflective layer has a higher stiffness than another portion of the movable reflective layer that is not on the at least one free edge.

10. A system comprising:

a display comprising a plurality of display elements of claim 1;

a processor that is configured to communicate with said display, said processor being configured to process image data; and

a memory device that is configured to communicate with said processor.

11. The system as recited in claim 10, further comprising a driver circuit configured to send at least one signal to said display.

12. The system as recited in claim 11, further comprising a controller configured to send at least a portion of said image data to said driver circuit.

13. The system as recited in claim 10, further comprising an image source module configured to send said image data to said processor.

14. The system as recited in claim 13, wherein said image source module comprises at least one of a receiver, transceiver, and transmitter.

15. A display element comprising:

a plurality of interferometric modulator devices configured in a matrix forming a plurality of rows and columns, each interferometric modulator device comprising

a movable reflective layer comprising two opposite edges that are each supported by a rail and two opposing free edges, and

a plurality of posts configured to support the movable reflective layer, the plurality of posts being spaced apart to define post spacing distances between adjacent posts positioned along an axis parallel to one of the rails, wherein an outer post spacing distance between two adjacent outer posts along the axis is smaller than an inner post spacing distance between two adjacent inner posts along the axis, where the outer posts are closer to a free edge than the inner posts.

16. The display element of claim 15, wherein the post spacing distances between a plurality of adjacent inner posts along the axis are substantially the same.

17. The display element of claim 15, wherein the post spacing distances between the adjacent outer posts close to the respective free edges are substantially the same.

18. The display element of claim 15, wherein the post spacing distances between adjacent inner posts along the axis increase as the distance from one of the free edges increases.

19. The display element of claim 15, wherein the post spacing distance between two adjacent outer posts along the axis and closest to each free edge is approximately 32 μ

m.

20. The display element of claim 15, wherein the post spacing distance between two adjacent inner posts along the axis is approximately 38 μ

m.

21. The display element of claim 15, wherein the post spacing distance between two adjacent outer posts along the axis and closest to each free edge is approximately 2-10 μ

m smaller than the post spacing distance between two adjacent inner posts along the axis.